CN113480983A - Drilling fluid composition for protecting oil-gas reservoir and preparation method and application thereof - Google Patents
Drilling fluid composition for protecting oil-gas reservoir and preparation method and application thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/02—Well-drilling compositions
- C09K8/04—Aqueous well-drilling compositions
- C09K8/14—Clay-containing compositions
- C09K8/16—Clay-containing compositions characterised by the inorganic compounds other than clay
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/02—Well-drilling compositions
- C09K8/04—Aqueous well-drilling compositions
- C09K8/14—Clay-containing compositions
- C09K8/18—Clay-containing compositions characterised by the organic compounds
- C09K8/22—Synthetic organic compounds
- C09K8/24—Polymers
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Abstract
The invention relates to the field of oil and gas well engineering drilling fluid, and discloses a drilling fluid composition for protecting an oil and gas reservoir, and a preparation method and application thereof. The drilling fluid composition for protecting the oil-gas reservoir contains water, bentonite, sodium carbonate, a tackifier, a filtrate reducer, an anti-collapse agent, a lubricant and a weighting agent. The anti-collapse agent is modified high-molecular wax, the lubricant is methyl oleate, and the weighting agent is polyethylene glycol surface-modified barium carbonate. The modified barium carbonate which can be dissolved in acid is used in the invention, the density is high, the grinding property is low, mud cakes formed by the weighted drilling fluid are high in acid solubility, the problems that a barite weighting agent is difficult to dissolve in acid and blocks an oil-gas layer can be avoided, and the density of the drilling fluid after the barite weighting is used can be close to that of the barite weighting. The invention has certain significance for protecting the oil-gas reservoir and improving the yield of oil gas.
Description
Technical Field
The invention relates to the field of oil and gas well engineering drilling fluid, in particular to a drilling fluid composition for protecting an oil and gas reservoir and a preparation method and application thereof.
Background
The protection of hydrocarbon reservoir is one of the important technical measures in the process of petroleum exploration and development, and the quality of the work is directly related to the exploration and development effects. During the well drilling and completion process, if no effective measures for protecting the hydrocarbon reservoir are taken, the hydrocarbon well can be seriously damaged, which is directly marked by the reduction of the permeability of the hydrocarbon reservoir. Resulting in a significant reduction in fluid production or chasing ability.
During the conventional positive pressure differential overbalanced drilling, various solid-phase particles carried in the drilling fluid can fill and block the pores of the formation cracks, wherein the heavy weight material barite is abundant. The main component of the barite is barium sulfate which is insoluble salt, and the barite enters the pore throat and the cracks of an oil-gas layer under the action of pressure difference formed between effective liquid column pressure of drilling fluid and formation pore pressure to cause damage to the oil-gas layer, and the severity of the damage is increased along with the increase of solid phase content in drilling fluid, particularly the content of the barite.
The drilling fluid is the working fluid which is firstly contacted with the stratum in the drilling operation, the type and the performance of the drilling fluid are directly related to the damage degree to an oil-gas layer, and the protection of the drilling fluid in the oil-gas layer is the first technical link for protecting the operation of the oil-gas layer. Therefore, the novel modified barium carbonate weighting agent is prepared, the drilling fluid for protecting the oil-gas reservoir is established, and when the oil well is put into operation, the inner and outer filter cakes of the well wall of the oil-gas reservoir can be eliminated through acidification, so that the blockage of the weighting agent particles is relieved, and the method has important significance for the efficient development of the oil-gas reservoir and the improvement of the oil-gas recovery ratio.
Disclosure of Invention
The invention provides a drilling fluid composition for protecting a hydrocarbon reservoir, so as to solve the problem that the permeability is reduced and the hydrocarbon reservoir is damaged because solid-phase particles (particularly barite particles) block the hydrocarbon reservoir in the drilling process of the conventional drilling fluid. The drilling fluid composition for protecting the oil-gas reservoir contains water, bentonite, sodium carbonate, a tackifier, a filtrate reducer, an anti-collapse agent, a lubricant and a weighting agent.
The invention provides a preparation method of the protective hydrocarbon reservoir drilling fluid weighting agent, wherein the method comprises the following steps:
(1) dispersing barium carbonate in a solvent to obtain a dispersion liquid;
(2) introducing sufficient carbon dioxide into said dispersion;
(3) dispersing polyethylene glycol in the dispersion liquid for surface modification;
(4) and (4) washing, centrifuging, drying and stripping the product obtained in the step (3).
In a third aspect, the invention provides a preparation method and an application of the drilling fluid composition, wherein the method comprises the following steps:
(S1) adding bentonite in required amount into desalted water or tap water at 80 deg.C to obtain mixed solution 1.
(S2) adding a required amount of sodium carbonate into the mixed solution 1 obtained in the step (S1), stirring, adjusting the pH value of the system to 10.0 by using sodium hydroxide, and pre-hydrating for 24 hours to obtain a mixed solution 2.
(S3) adding required amount of sodium carbonate, tackifier, filtrate reducer, anti-collapse agent, lubricant and weighting agent into the mixed solution 2 obtained in the step (S2) in sequence under stirring state, and mixing uniformly to obtain the drilling fluid for protecting the oil-gas reservoir.
Through the technical scheme, the barium carbonate is subjected to surface modification to prepare the weighting agent with stronger dispersity, has the characteristics of high density, low abrasion damage to drilling tools and strong acid solubility, and is an excellent drilling fluid weighting material. The drilling fluid prepared by the weighting agent is beneficial to protecting an oil-gas layer, the mud cake acid solubility is high, the permeability recovery value is high, and later acidification and blockage removal measures are beneficial to being adopted.
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
In a first aspect, the invention provides a drilling fluid composition for protecting hydrocarbon reservoirs, wherein the drilling fluid composition comprises water, bentonite, sodium carbonate, a tackifier, a fluid loss additive, an anti-collapse agent, a lubricant and a weighting agent. The tackifier is polyacrylamide sylvite KPAM, the filtrate reducer is sulfonated phenolic resin SMP-3, the anti-collapse agent is modified high molecular wax SMXFT, the lubricant is methyl oleate, and the polyethylene glycol surface modified barium carbonate.
According to the invention, the molecular weight of the tackifier is 10-500 ten thousand, preferably, the molecular weight of the tackifier is 20-90 ten thousand;
according to the invention, the particle size distribution of the anti-collapse agent is 0.1-30 μm, preferably, the particle size distribution of the anti-collapse agent is 0.1-15 μm;
according to the invention, the particle size distribution of the weighting agent is between 0.2 and 100 μm, preferably the particle size distribution of the weighting agent is between 0.8 μm and 45 μm, respectively.
According to the invention, the drilling fluid composition for protecting the oil-gas reservoir comprises the following raw materials in parts by weight: 100 parts by weight of water; 2-6 parts of bentonite; 0.1-1 part by weight of sodium carbonate; 1-10 parts of a fluid loss additive; 1-10 parts of an anti-collapse agent; 0.1-5 parts by weight of a lubricant; 150 portions and 200 portions of weighting agent.
According to the invention, through strictly controlling the content of each component, the components can interact with each other, so that the prepared drilling fluid composition can exert the optimal effect in the drilling process.
Preferably, based on 100 parts by weight of water; 3-5 parts of bentonite; 0.1-1 part by weight of sodium carbonate; 1-6 parts of a fluid loss additive; 1-5 parts of an anti-collapse agent; 0.1-2 parts of lubricant; when the weighting agent is 160-180 parts by weight, the effect is better.
According to the invention, the fluid loss additive may be a sulfonated phenolic resin SMP-3, commercially available. The water aqua is a colloid product obtained by polymerizing and sulfonating phenol, formaldehyde and sulfonate for many times under certain conditions. The molecular structure contains benzene ring, methylene bridge and C-S bond, has strong thermal stability, and is a high temperature resistant fluid loss agent.
According to the invention, the anti-collapse agent can be modified polymer wax SMXFT, and can be obtained commercially. The asphalt has good anti-collapse performance and oil-gas reservoir protection effect, and overcomes the defects of high toxicity, high fluorescence level and the like of asphalt products. The modified high molecular wax is a product of fatty alcohol resin after water-soluble processing, can generate emulsification with water and clay, can form tough particles at different temperatures, block stratum microcracks and pores of permeable stratum, play a role in reducing filtration loss, preventing stratum collapse and protecting oil-gas layers, cannot interfere geological logging, has regular well diameter, smooth electrical measurement, is safe underground, is easy to biodegrade, is nontoxic and is an environment-friendly drilling fluid additive.
According to the present invention, the lubricant may be methyl oleate, which is commercially available. Methyl oleate is also called cis-9-octadecenoic acid methyl ester, has a chemical molecular formula of C19H36O2, has a structural formula of CH3(CH2)7CH (CH2)7COOCH3, is colorless to light yellow oily liquid, is combustible and insoluble in water, and is mutually soluble with organic solvents such as ethanol, diethyl ether and the like. The lubricant is an unsaturated high-grade fatty acid ester, an important chemical raw material, is widely used in the petroleum drilling industry, is used for a non-fluorescent drilling fluid lubricant, effectively improves the adsorbability of mud cakes and metal surfaces of drilling tools, reduces the adhesion coefficient by effectively improving the wettability, has good thermal stability and good compatibility, can be uniformly dispersed, and is a petroleum exploration non-fluorescent drilling fluid lubricant.
In a second aspect, the invention provides a method for preparing a weighting agent for drilling fluid in a protected hydrocarbon reservoir. The anti-collapse agent is barium carbonate subjected to surface modification by polyethylene glycol, and the preparation method comprises the following steps:
(1) dispersing barium carbonate in a solvent to obtain a dispersion liquid;
(2) introducing sufficient carbon dioxide into said dispersion;
(3) dispersing polyethylene glycol in the dispersion liquid for surface modification;
(4) and (4) washing, centrifuging, drying and stripping the product obtained in the step (3).
The production method according to the present invention, wherein, in the step (1), the solvent is methanol; preferably, the amount of barium carbonate used is 5-10g, corresponding to 100mL of said solvent.
The preparation method provided by the invention, wherein in the step (2), the reaction conditions are that the temperature is 50-60 ℃, the stirring speed is 600-1200r/min, and the time is 60-90 min.
The preparation method according to the invention, wherein, in the step (3), the modification condition is that in an oil bath kettle, the stirring rate is 600-.
The preparation method provided by the invention is characterized in that in the step (4), the separation condition is a centrifugal rotating speed of 6000r/min-9000 r/min; the drying condition is that the temperature is 80-120 ℃, and the drying time is 4-6 h; the stripping condition is that the obtained product is ultrasonically stripped in an ultrasonic instrument, the ultrasonic frequency is 3-4MHz, and the time is 50-70 min.
The aim of this is to make the barium carbonate more dispersible and less prone to agglomeration. When the filter fluid is used for wall building, an outer mud cake can be quickly formed, the filter loss is reduced, and solid-phase particles in the drilling fluid are prevented from further moving to the deep part of the stratum.
In a third aspect, the invention provides a method for preparing a drilling fluid composition for protecting hydrocarbon reservoirs and applications thereof. The preparation method of the drilling fluid composition comprises the following steps:
(S1) adding bentonite in required amount into desalted water or tap water at 80 deg.C to obtain mixed solution 1.
(S2) adding a required amount of sodium carbonate into the mixed solution 1 obtained in the step (S1), stirring, adjusting the pH value of the system to 10.0 by using sodium hydroxide, and pre-hydrating for 24 hours to obtain a mixed solution 2.
(S3) adding required amount of sodium carbonate, tackifier, filtrate reducer, anti-collapse agent, lubricant and weighting agent into the mixed solution 2 obtained in the step (S2) in sequence under stirring state, and uniformly mixing to obtain the drilling fluid for protecting the oil-gas reservoir.
According to the invention, the bentonite is calcium bentonite, and pre-hydration treatment is required before the drilling fluid is prepared. Heating a certain amount of desalted water or tap water to more than 80 ℃, adding bentonite with 4% of water, fully stirring until the bentonite is fully dispersed and has no agglomeration, adding Na2CO3 with 5% of bentonite, adjusting the pH value to 10 by using NaOH, stirring for 2 hours at the stirring speed of 200r/min-600r/min, and standing for more than 24 hours. The aim of this is to improve the slurrying capacity of the calcium bentonite, so that the drilling fluid has a better flow pattern.
Compared with the traditional water-based drilling fluid system, the drilling fluid for protecting the hydrocarbon reservoir provided by the invention has the following advantages when drilling into the hydrocarbon reservoir:
(1) the barium carbonate is completely suitable for weighting of various drilling fluid systems, and the density of the weighted drilling fluid can be completely similar to that of barite.
(2) Barium carbonate is a weighting agent with strong acid solubility, and the acid solubility of the weighted drilling fluid mud cake can reach more than 90 percent, which is superior to ilmenite powder. The drilling fluid system is low in toxicity, environment-friendly and environment-friendly. The anti-collapse agent is non-toxic and degradable, can be used as a reservoir protection agent, and does not influence the operation of logging.
(3) The drilling fluid has strong suspension stability, and the phenomenon of a large amount of solid phase sedimentation and accumulation of the circulating drilling fluid after the pump is stopped in the drilling process can not occur. The capability of suspending and carrying rock debris is strong during circulation.
The routes of purchase of the drug and the instruments required for testing according to the present invention are described in detail below.
Electronic balance, accuracy 0.0001g, purchased from Shanghai balance instrumentation works;
the bentonite can be Xinjiang Xiazijie bentonite purchased from Xinjiang non-Xiazijie Bentonite GmbH;
sodium carbonate is available from Beijing Yinaoka technologies, Inc., under the product number A88871;
the fluid loss additive sulfonated phenolic resin can be purchased from Chengdu Xiyouhua Wei science and technology Limited company, model SMP-3;
methanol is available from Shanghai Saisha technology Limited, cat # C42395;
the polyethylene glycol can be a product obtained from Shanghai Chungsai science and technology Limited, with a product number PMC 172016161;
barium carbonate can be purchased from Shanghai chemical industry Co., Ltd, Cat. No. 026-08762;
the tackifier polyacrylamide potassium salt can be purchased from Hebei Yanxing chemical Co., Ltd, model KPAM;
the anti-collapse agent modified polymer wax can be purchased from Gongshida Taurushijiu, Inc., model number SMXFT;
the lubricant methyl oleate may be available from chemical company Limited, Waverrucke, Beijing, under the product number M875676;
preparation example 1
This preparation example is intended to illustrate the process for preparing the modified barium carbonate weighting agent of the present invention
Dispersing 5g of barium carbonate in 100mL of methanol, introducing carbon dioxide into an oil bath pan at the temperature of 50 ℃ and the stirring speed of 900r/min, mixing and stirring for 70min, stopping introducing the carbon dioxide, adding 3g of polyethylene glycol into the dispersion, and reacting for 4h at the temperature of 80 ℃. Repeatedly centrifuging the mixed solution with deionized water to neutrality at 9000r/min, drying the obtained solid in a blast oven at 100 deg.C for 4h, ultrasonically stripping the obtained product in an ultrasonic instrument for 60min at ultrasonic frequency of 3.5MHz to obtain a modified barium carbonate weighting agent
The prepared modified barium carbonate weighting agent is white powder and is insoluble in water. The density was measured to be 4.26g/cm3The acid solubility was 92.4%.
Preparation example 2
This preparation example is intended to illustrate the process for preparing the modified barium carbonate weighting agent of the present invention
And (3) dispersing 7.5g of barium carbonate in 100mL of methanol, introducing carbon dioxide into an oil bath pan at the temperature of 50 ℃ and the stirring speed of 900r/min, mixing and stirring for 70min, stopping introducing the carbon dioxide, adding 5g of polyethylene glycol into the dispersion, and reacting for 4h at the temperature of 80 ℃. Repeatedly centrifuging the mixed solution with deionized water to neutrality at 9000r/min, drying the obtained solid in a blast oven at 100 deg.C for 4h, ultrasonically stripping the obtained product in an ultrasonic instrument for 60min at ultrasonic frequency of 3.5MHz to obtain a modified barium carbonate weighting agent
The modified barium carbonate is preparedThe weighting agent is white powder and is insoluble in water. The density was measured to be 4.30g/cm3The acid solubility was 93.8%.
Preparation example 3
This preparation example is intended to illustrate the process for preparing the modified barium carbonate weighting agent of the present invention
And dispersing 10g of barium carbonate in 100mL of methanol at the temperature of 50 ℃, introducing carbon dioxide into an oil bath kettle at the stirring speed of 900r/min, mixing and stirring for 70min, stopping introducing the carbon dioxide, adding 7g of polyethylene glycol into the dispersion, and reacting for 4h at the temperature of 80 ℃. Repeatedly centrifuging the mixed solution with deionized water to neutrality at 9000r/min, drying the obtained solid in a blast oven at 100 deg.C for 4h, ultrasonically stripping the obtained product in an ultrasonic instrument for 60min at ultrasonic frequency of 3.5MHz to obtain a modified barium carbonate weighting agent
The prepared modified barium carbonate weighting agent is white powder and is insoluble in water. The density was measured to be 4.19g/cm3The acid solubility was 92.4%.
Example 1
This example illustrates a protected hydrocarbon reservoir drilling fluid and method of making the same according to the present invention.
Heating 100 parts by weight of tap water to 80 ℃, uniformly adding 4 parts by weight of bentonite when the bentonite is fully dispersed and does not agglomerate under the electric stirring of 600r/min, adding 0.15 part by weight of sodium carbonate, adjusting the pH value to 10 by using NaOH, stirring for 2 hours, and standing for more than 24 hours. Adding 0.2 part by weight of tackifier under the condition of electric stirring at 600r/min, adding 4 parts by weight of filtrate reducer SMP-3, stirring for 10min, adding 3.0 parts by weight of anti-collapse agent SMXFT, stirring for 10min, adding 0.2 part by weight of lubricant, stirring for 10min, adding 170 parts by weight of modified barium carbonate weighting agent prepared in the preparation example (1), and stirring for 10min at the rotating speed of 6000r/min by using a high-speed stirrer to obtain the drilling fluid.
The results of the conventional performance test of the drilling fluid are shown in table 1, and the results of the permeability recovery performance test are shown in table 2.
Example 2
Drilling fluids were prepared in the same manner as in example 1, except that: 170 parts by weight of the modified barium carbonate weighting agent prepared in preparation example (2) was replaced with the modified barium carbonate weighting agent used in the examples.
The results of the conventional performance test of the drilling fluid are shown in table 1, and the results of the permeability recovery performance test are shown in table 2.
Example 3
Drilling fluids were prepared in the same manner as in example 1, except that: 170 parts by weight of the modified barium carbonate weighting agent prepared in preparation example (3) was replaced with the modified barium carbonate weighting agent used in the examples.
The results of the conventional performance test of the drilling fluid are shown in table 1, and the results of the permeability recovery performance test are shown in table 2.
Comparative example 1
Drilling fluids were prepared in the same manner as in example 1, except that: the addition amount of the modified barium carbonate weighting agent is 0 part by weight.
The results of the conventional performance test of the drilling fluid are shown in table 1, and the results of the permeability recovery performance test are shown in table 2.
Comparative example 2
Drilling fluids were prepared in the same manner as in example 1, except that: the amount of the anti-collapse agent added is 0 part by weight.
The results of the conventional performance test of the drilling fluid are shown in table 1, and the results of the permeability recovery performance test are shown in table 2.
Comparative example 3
Drilling fluids were prepared in the same manner as in example 1, except that: the addition amount of the anti-collapse agent and the weighting agent is 0 part by weight.
The results of the conventional performance test of the drilling fluid are shown in table 1, and the results of the permeability recovery performance test are shown in table 2.
Comparative example 4
Drilling fluids were prepared in the same manner as in example 1, except that: the weighting agent used is common commercial barium sulfate barite, and the addition amount is 170 parts by weight.
The results of the conventional performance test of the drilling fluid are shown in table 1, and the results of the permeability recovery performance test are shown in table 2.
Comparative example 5
Drilling fluids were prepared in the same manner as in example 1, except that: the weighting agent used was magnetite in an amount of 170 parts by weight.
The results of the conventional performance test of the drilling fluid are shown in table 1, and the results of the permeability recovery performance test are shown in table 2.
Comparative example 6
Drilling fluids were prepared in the same manner as in example 1, except that: the weighting agent used was calcium carbonate added in an amount of 170 parts by weight.
The results of the conventional performance test of the drilling fluid are shown in table 1, and the results of the permeability recovery performance test are shown in table 2.
Test example 1
The conventional performance of the drilling fluids prepared in examples 1 to 3 and comparative examples 1 to 6 was measured by a densitometer, a six-speed rotational viscometer and a high-temperature high-pressure fluid loss filter.
TABLE 1 results of conventional Performance testing
From the data in table 1, it can be seen that:
for a permeable hydrocarbon reservoir, the higher the amount of water lost at high temperature and pressure indicates that the solid and liquid phases invade deeper into the formation pores and are therefore more harmful to the reservoir. Therefore, the drilling fluids of examples 1-3 have good rheological property and static shear force, high-temperature and high-pressure filtration loss of 9.0-9.6ml and mud cake thickness of 3.2-3.5mm, have better filtration and wall-building properties compared with comparative examples 1-6, and the drilling fluids prepared in a limited range of proper components and contents have excellent filtration and wall-building properties, can form thin and compact mud cakes on well walls, and reduce invasion of solid and liquid phases of the drilling fluids into stratums and damage of oil and gas layers.
For the density after weighting, the weighting effect of the modified barium carbonate weighting agent is equivalent to that of the common commercial barite weighting agent, is superior to calcium carbonate and is slightly inferior to iron ore powder. However, the calcium carbonate has lower density, and has larger influence on the rheological property and the viscous cutting property of the drilling fluid after being weighted.
In the comparative example 1, the drilling fluid is not weighted by the modified barium carbonate weighting agent, the water loss of the drilling fluid is up to 35.8ml, which indicates that large-particle bridging particles are absent in a drilling fluid system, a large number of crack pores in a stratum cannot be blocked, a compact mud cake cannot be formed, and the safe drilling is not facilitated.
In the comparative example 2, the drilling fluid is not added with an anti-collapse agent, the high-temperature water loss is up to 16.4ml, and a large amount of filtrate enters rock pores to increase the pore pressure in the stratum, so that the complex occurrence of borehole wall instability and collapse is easily caused.
In the comparative example 3, no weighting agent or anti-collapse agent is added, and the high-temperature high-pressure water loss of the drilling fluid is up to 42.8ml, which is not favorable for normal drilling and the requirement of reservoir protection.
The drilling fluid in the comparative example 4 is weighted by using common commercial barite, the conventional performances of the drilling fluid are equivalent to those of the drilling fluid in the examples, and the high-temperature high-pressure filtration loss and the mud cake thickness are slightly higher than those of the drilling fluid weighted by the modified barium carbonate.
The drilling fluid in comparative example 5, weighted with iron ore fines, was superior to the drilling fluid of the examples in terms of density and slightly inferior to the drilling fluid of the examples in terms of high temperature and high pressure fluid loss.
The drilling fluid in comparative example 6 was weighted with calcium carbonate and the performance of the drilling fluid was inferior to the drilling fluid in the examples.
Test example 2
And (3) respectively taking a proper amount of the drilling fluid prepared in the examples 1-3 and the comparative examples 1-6, dynamically evaluating the oil phase permeability of the rock core before and after the drilling fluid is polluted by using a reservoir damage evaluation device, and inspecting the oil-gas layer protection performance of the drilling fluid according to the ratio of the oil phase permeability. 3D printing artificial rock cores are selected for testing, and the parameters are shown in table 2.
Table 2 results of the flow test of drilling fluid in artificial core
As can be seen from Table 2, in the permeability recovery test of the artificial rock core, after the drilling fluid polluted by the weighted drilling fluid of the modified barium carbonate weighting agent, the permeability recovery value of the rock core is over 90 percent, which is obviously superior to that of the weighted drilling fluid of the common commercial barite.
In conclusion, the drilling fluid for protecting the oil-gas layer is weighted by adding the modified barium carbonate weighting agent, has high permeability recovery value after the artificial core is blocked by flowing, has good filtration and wall building properties, can form thin and compact mud cakes, and prevents the penetration of the filtrate of the drilling fluid to permeable pores. The oil-gas well has good weighting effect and is easy to dissolve in acid, thereby being beneficial to protecting an oil-gas layer and improving the recovery ratio of the oil-gas well.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of technical features in any other suitable way, and these simple modifications and combinations are also regarded as the disclosure of the invention and fall within the scope of the invention.
Claims (10)
1. The drilling fluid for protecting the oil-gas reservoir is characterized by comprising water, bentonite, sodium carbonate, a tackifier, a filtrate reducer, an anti-collapse agent, a lubricant and a weighting agent, wherein the tackifier is polyacrylamide sylvite KPAM, the filtrate reducer is sulfonated phenolic resin SMP-3, the anti-collapse agent is modified high-molecular wax SMXFT, the lubricant is methyl oleate, and the polyethylene glycol surface-modified barium carbonate.
2. A protected hydrocarbon reservoir drilling fluid composition as claimed in claim 1 wherein the particle size distribution of the anti-sloughing agent is 0.1-30 μm; preferably, the particle size distribution of the anti-collapse agent is 0.1-15 μm.
3. A drilling fluid composition according to claims 1 and 2. The weight portions of the raw materials are as follows: 100 parts by weight of water; 2-6 parts of bentonite; 0.1-1 part by weight of sodium carbonate; 1-10 parts of a fluid loss additive; 1-10 parts of an anti-collapse agent; 0.1-5 parts by weight of a lubricant; 150 portions and 200 portions of weighting agent.
4. The drilling fluid composition of any of claims 1-3, wherein the weighting agent modified barium carbonate is prepared by a method comprising the steps of:
(1) dispersing barium carbonate in a solvent to obtain a dispersion liquid;
(2) introducing sufficient carbon dioxide into said dispersion;
(3) dispersing polyethylene glycol in the dispersion liquid for surface modification;
(4) and (4) washing, centrifuging, drying and stripping the product obtained in the step (3).
5. The production method according to claim 4, wherein, in step (1), the solvent is methanol; preferably, the amount of barium carbonate used is 5-10g, corresponding to 100mL of said solvent.
6. The preparation method according to claim 4, wherein, in the step (2), the reaction conditions are a temperature of 50-60 ℃, a stirring rate of 600-.
7. The preparation method according to claim 4, wherein in the step (3), the modification condition is that a fixed amount of polyethylene glycol is added to the dispersion at regular intervals in an oil bath kettle at a stirring rate of 600-1200r/min, and the reaction is continued for 4-6h at a temperature of 60-80 ℃, preferably, the cumulative addition amount of polyethylene glycol is 2-8g relative to 100mL of the dispersion.
8. The production method according to claim 4, wherein, in step (4), the separation conditions are a centrifugal rotation speed of 6000r/min to 9000 r/min; the drying condition is that the temperature is 80-120 ℃, and the drying time is 4-6 h; the stripping condition is that the obtained product is ultrasonically stripped in an ultrasonic instrument, the ultrasonic frequency is 3-4MHz, and the time is 50-70 min.
9. A protected hydrocarbon reservoir drilling fluid according to any one of claims 1 to 8, wherein the method comprises:
(S1) adding bentonite with required amount into desalted water or tap water with the temperature of more than 80 ℃ to obtain mixed solution 1;
(S2) adding a required amount of sodium carbonate into the mixed solution 1 obtained in the step (S1), stirring, adjusting the pH value of the system to 10.0 by using sodium hydroxide, and pre-hydrating for 24 hours to obtain a mixed solution 2;
(S3) adding required amount of sodium carbonate, tackifier, filtrate reducer, anti-collapse agent, lubricant and weighting agent into the mixed solution 2 obtained in the step (S2) in sequence under stirring state, and uniformly mixing to obtain the drilling fluid for protecting the oil-gas reservoir.
10. The drilling fluid composition of any one of claims 1-8 or the drilling fluid composition prepared by the preparation method of claim 9 can prevent reservoir plugging damage, is beneficial to oil testing and geological condition understanding, and can accelerate oil and gas exploration.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110814676.4A CN113480983A (en) | 2021-07-19 | 2021-07-19 | Drilling fluid composition for protecting oil-gas reservoir and preparation method and application thereof |
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| CN202110814676.4A CN113480983A (en) | 2021-07-19 | 2021-07-19 | Drilling fluid composition for protecting oil-gas reservoir and preparation method and application thereof |
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| CN202110814676.4A Pending CN113480983A (en) | 2021-07-19 | 2021-07-19 | Drilling fluid composition for protecting oil-gas reservoir and preparation method and application thereof |
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Cited By (1)
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| CN114152555A (en) * | 2022-02-09 | 2022-03-08 | 成都理工大学 | Drilling fluid leakage damage simulation device and method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114152555A (en) * | 2022-02-09 | 2022-03-08 | 成都理工大学 | Drilling fluid leakage damage simulation device and method |
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Application publication date: 20211008 |